Pedal actuated steering clutch and brake controls for tractors

ABSTRACT

.Iadd.The steering clutches and steering brakes of a tractor are operated by foot pedals. Each of two pedals operates to release its respective clutch and apply the corresponding brake. A third pedal, located intermediate the other two, applies both brakes without operating the clutches. .Iaddend.

This invention relates to the steering of tractors and particularly tosteering entirely by pedal actuated controls, of the type of tractorwhich is designed for steering by driving or by braking.

In track-type tractors and some wheel-type tractors steering isaccomplished by interrupting the drive to the drive wheel or sprocket onone side or the other of the tractor and may also be accomplished byapplying a brake selectively to the right or left drive component.Conventionally the steering clutch controls of such tractors areoperable by hand levers and the steering brake controls include footpedals.

In the operation of present day tractor mounted equipment such asbulldozers and bucket loaders, various hand controls such as hydraulicvalves require actuation and it is desirable that driving and steeringbe accomplished as much as possible by pedal controls to free the handsof the operator for efficient operation of various machine attachments.

It is, therefore, an object of the present invention to provide atractor, the steering of which may be accomplished entirely throughpedals.

A further object of the invention is to provide steering controls for atractor including two pedals, each of which is operable to release asteering clutch on one side of the tractor and to apply a steering brakeon the same side of the tractor.

A further object of the invention is to provide a tractor with suchpedal operated steering clutch and brake actuating mechanisms in whichthe pedals are operable for gradual release of the clutches andapplication of the brake only after complete clutch release or in whichthe pedals may be actuated to effect quick clutch release and quickapplication of the brakes for fast steering.

A further object of the invention is to provide a single pedal foroperation of both steering brakes simultaneously with equal pressure andwithout releasing the clutches.

Still further and more specific objects and advantages of the inventionand the manner in which the invention is carried into practice are madeapparent in the following specification wherein reference is made to theaccompanying drawings.

In the drawings:

FIG. 1 is a fragmentary perspective view with parts broken away andparts in section illustrating steering controls embodying the presentinvention;

FIG. 2 is an enlarged sectional view of an hydraulic servo which forms apart of the invention illustrated in FIG. 1; and

FIG. 3 is a view like FIG. 2 illustrating the parts of the servo indifferent positions.

An operator's station of a tractor is illustrated in FIG. 1 ascomprising a deck 10 and a seat 11 with foot pedals arranged as shownwithin convenient reach of an operator in the seat. Right and leftsteering clutches of the tractor (not shown) are operable by a pair ofsteering clutch valves 12, shown in broken lines in FIG. 1, one of whichis also shown in FIGS. 2 and 3. Each steering clutch valve is actuatedby engagement of a lever 14 with the end of a plunger 15 (see FIG. 2)through the medium of an anti-friction roller 16.

A pair of brake and clutch pedals 18L and 18R is employed to actuate theleft and right clutch valves, respectively, and also to actuate left andright brakes as will presently be described in detail. The linkagebetween the pedals and the clutch valves is substantially identical onthe left and right hand side and comprises first a shaft 19 supportingthe pedals for pivotal movement and springs 20 arranged to urge thepedals toward retracted positions. Links 21 form connections between thepedals and bellcrank assemblies, generally indicated at 22, and links 23connect the bellcrank assemblies to crank arms 24 on shafts whichsupport the levers 14 which actuate the plungers 15. Consequentlydepression of either of the pedals 18 will actuate the correspondingclutch valve to disengage the selected clutch for effecting steering ofthe tractor.

Left and right hand steering brakes of conventional type are containedin housings 26L and 26R are operable by the same pedals 18L and 18R onlyafter disengagement of the corresponding clutches. The brakes areadapted to be applied by brake levers 28L and 28R pivoted on the shaft19 and retracted as by springs 29. These levers are connected by links30 with brake actuating levers 31 capable of applying the brakescontained in the housings 26L and 26R by conventional mechanism theconstruction of which is not necessary to an understanding of thepresent invention. Each of the clutch and brake pedals 18L and 18R isprovided with a lug 33 which upon depression of either pedal engages thecorresponding brake lever 28L and 28R. The brake levers causeapplication of the brakes after taking up lost motion in the brakemechanism and permitting initial disengagement of the clutches throughthe steering clutch valves 12 in a manner presently to be described indetail.

It is also desirable that both brakes be capable of applicationsimultaneously and independently of the steering clutches and this isaccomplished by a third pedal 35 disposed intermediate the pedals 18Land 18R and also pivotally supported on the shaft 19 and urged toward aretracted position by a spring 36. This pedal carries an equalizing bar38 pivoted as at 39 to brackets on the pedal and extending outwardly toengage both of the pedal actuating levers 28L and 28R. It is obviousthat depression of the pedal 35 will effect application of both of thesteering brakes and since the equalizing bar is pivoted, the forceapplied to the brakes is equalized to avoid excessive wear on eitherbrake. Pivotal movement of the equalizer bar is limited by lugs 40 andstops 41. The brake pedal 35 may be employed to stop the tractor whenits motion is being controlled by a main clutch in association with thetractor transmission rather than by the steering clutches. This brakepedal is therefore useable in accurately positioning the tractor when animplement such as a blade or bucket is being poised for a givenoperation and the tractor may in such cases be brought to a halt withthe operation of one foot while the operator's hands are occupied withother controls.

The construction of the steering clutch valves which enables operationof the pedals 18L and 18R to first disengage the clutches and then applythe brakes is best illustrated in FIGS. 2 and 3. In these figures, eachvalve is shown as having a reciprocable plunger 15 normally retracted asby a spring 45. The inner end of the plunger is slidably arranged in acentral bore of a piston 46 reciprocably disposed in a bore 47 in thehousing. Fluid under pressure from a source (not shown) which may be thelubricating oil system of the tractor engine is introduced through aport 48 to the space behind the piston 46 and is normally vented throughports 50 in the plungers and ports 51 in the forward end of the piston46.

Upon depression of one of the pedals 18L or 18R to disengage itscorresponding clutch, the plunger 15 is advanced until the ports 50therein are closed by entering the bore in the piston (see FIG. 3) andconsequently pressure builds up behind the piston to advance it. Thisactuates a lever 52 with an anti-friction roller 53 thereon and rotatesa shaft 54 to effect clutch disengagement through conventional mechanism(not shown). Upon complete clutch disengagement, relief ports 56 in thewalls of the piston 46 extend beyond the end of the housing 12 torelieve pressure as in the piston shown in FIG. 3, thus preventingfurther actuation of the clutch disengaging leverage. From thisposition, which represents approximately three inches of travel of theactuating pedals 18L and 18R, further pedal movement is required toeffect actuation of a brake. This further pedal movement which isaccompanied by further swinging movement of the valve actuating lever 14is made possible by providing space in the piston 46 into which theplunger 15 may travel without changing the condition of the steeringclutches ordinarily controlled by its movement. Thus the plunger maytravel to the dotted line position illustrated in FIG. 3 where its innerend is received within the hollow interior of the piston 46 so that thebrakes may be applied after clutch disengagement and while the clutchesare retained in their disengaged positions.

We claim:
 1. In a tractor which has steering clutches and steering brakes, the combiation comprising: .Iadd.first and second .Iaddend.actuating members for said clutches and brakes, .Iadd.a fluid-operated clutch disengaging valve associated with each clutch, a .Iaddend.linkage .Iadd.arrangement to operate one clutch disengaging valve and .Iaddend.to release one clutch upon actuation of one member and to apply the corresponding brake upon further actuation of said one member, and .Iadd.a .Iaddend.similar linkage .Iadd.arrangement .Iaddend.between the other clutch and brake and the other member, .Iadd.each of said linkage arrangements including a first linkage from each actuating member to the corresponding clutch disengaging valve and a second separate linkage from each actuating member to the corresponding brake, .Iaddend.a third member and means operable upon actuation of said third member to apply both brakes only .Iadd.and without operating the clutches. .Iaddend. .[.2. The combination of claim 1 in which the linkages between the one and the other members include hydraulic valves and means in said valves to permit the further member actuation for applying the brakes after release of the clutches..].
 3. In a tractor which has steering clutches and steering brakes, the combination comprising: actuating pedals for said clutches and brakes, linkage to release one clutch upon depression of one pedal and to apply the corresponding brake upon further depression of said one pedal, similar linkage between the other clutch and brake and the other pedal, a third pedal .Iadd.disposed between the other two.Iaddend. , .[.and.]. means operable upon depression thereof to .[.apply.]. .Iadd.operate .Iaddend.both brakes only .Iadd., and said means including a member pivotally connected to the third pedal and engaging both linkages to equalize brake applying pressure.Iaddend. .
 4. .[.The combination of claim 3 in which.]. .Iadd.In a tractor which has steering clutches and steering brakes, the combination comprising: two actuating pedals for said clutches and brakes, linkage to release one clutch upon depression of one pedal and to apply the corresponding brake upon further depression of said one pedal, similar linkage between the other clutch and brake and the other pedal, a third pedal, means operable upon depression thereof to operate both brakes only, and .Iaddend.the linkages between the pedals and the clutches .[.include.]. .Iadd.including .Iaddend.hydraulic valves and means in said valves to permit the further pedal depression for applying the brakes after release of the clutches. .Iadd.
 5. The combination of claim 1 including means connected to the third member for engaging both said second separate linkages to equalize brake applying pressure. .Iaddend..Iadd.
 6. The combination of claim 1 in which each said linkage includes a first linkage to release the corresponding clutch, and a second separate linkage from each pedal to the corresponding brake; and in which the means operable upon depression of the third pedal includes the second separate linkages but not the first linkages. .Iaddend..Iadd.
 7. The combination of claim 6 in which the means operable upon depression of the third pedal also includes a member operatively connected to the third pedal for engaging both said second separate linkages to equalize brake applying pressure. .Iaddend. .Iadd.
 8. In a tractor which has steering clutches and steering brakes, the combination comprising: first and second actuating pedals for said clutches and brakes, a shaft and means for pivotally mounting the first and second pedals on the shaft, linkage to release one clutch upon depression of one pedal and to apply the corresponding brake upon further depression of said one pedal, similar linkage between the other clutch and brake and the other pedal, a third pedal, means for pivotally mounting the third pedal on the shaft intermediate the first and second pedals and generally colinear therewith, and means operable upon depression of the third pedal to apply both brakes only and without operating the clutches. .Iaddend..Iadd.
 9. The combination of claim 8 including a fluid-operated clutch disengaging valve associated with each clutch, and wherein the linkage is arranged to operate one clutch disengaging valve to release one clutch upon depression of one pedal. .Iaddend..Iadd.
 10. The combination of claim 8 in which each said linkage includes a first linkage to release the corresponding clutch, and a second separate linkage from each first and second pedal to the corresponding brake. .Iaddend. .Iadd.
 11. In a tractor which has steering clutches and steering brakes, the combination comprising: first and second actuating pedals for said clutches and brakes; a shaft and means for pivotally mounting the first and second pedals on the shaft; linkage to release one clutch upon depression of one pedal and to apply the corresponding brake upon further depression of said one pedal; similar linkage between the other clutch and brake and the other pedal; a third pedal; means for pivotally mounting the third pedal on the shaft intermediate the first and second pedals and generally colinear therewith; means operable upon depression of the third pedal to apply both brakes only; each said linkage including a first linkage to release the corresponding clutch, and a second separate linkage from each first and second pedal to the corresponding brake; and each second linkage including a lever pivotally mounted on the shaft at a position intermediate the third pedal and one of the first and second pedals. .Iaddend. .Iadd.
 12. The combination of claim 11 in which each lever is separate from but engageable by its adjacent pedal of the first and second pedals. .Iaddend..Iadd.
 13. The combination of claim 12 in which the means operable upon depression of the third pedal includes an outwardly-extending equalizer bar pivotally connected to the third pedal about an axis extending crosswise of the shaft and extending outwardly for engaging both levers when the third pedal is depressed to thereby apply both brakes without operating the clutches and without depressing the first and second pedals. .Iaddend..Iadd.
 14. The combination of claim 13 including stop means on the third pedal to limit pivotal movement of the equalizer bar. .Iaddend..Iadd.
 15. The combination of claim 13 including a fluid-operated clutch disengaging valve associated with each clutch, and wherein each first linkage is arranged to operate one clutch disengaging valve to release one clutch upon depression of one pedal. .Iaddend. .Iadd.
 16. In a tractor which has steering clutches and steering brakes, the combination comprising: first and second actuating pedals for said clutches and brakes; means for pivotally mounting the first and second pedals on the tractor at spaced positions; linkage to release one clutch upon depression of one pedal and to apply the corresponding brake upon further depression of said one pedal; similar linkage between the other clutch and brake and the other pedal; a third pedal; means for pivotally mounting the third pedal on the tractor at a position intermediate the first and second pedals; means operable upon depression of the third pedal to operate both brakes only; and said last-mentioned means including a first lever pivotally mounted on the tractor at a position intermediate the first and third pedals, a second lever pivotally mounted on the tractor at a position intermediate the second and third pedals, and a member pivotally mounted on the third pedal for engaging the first and second levers upon depression of the third pedal. .Iaddend. .Iadd.
 17. In a tractor which has steering clutches and steering brakes, the combination comprising: first and second actuating pedals for said clutches and brakes; a shaft and means for pivotally mounting the first and second pedals on the shaft; a linkage arrangement to release one clutch upon depression of one pedal and to apply the corresponding brake upon further depression of said one pedal; a similar linkage arrangement between the other clutch and brake and the other pedal; a third pedal; means for pivotally mounting the third pedal intermediate the first and second pedals and generally colinear therewith; means operable upon depression of the third pedal to apply both brakes only; each of said linkage arrangements including a first linkage to release the corresponding clutch, and a second separate linkage from each first and second pedal to the corresponding brake; each second linkage including a lever on the shaft at a position adjacent the pedals; each lever being separate from but engageable by its adjacent pedal of the first and second pedals; a fluid-operated clutch disengaging valve associated with each clutch; and each first linkage being arranged to operate one clutch disengaging valve to release one clutch upon depression of one pedal. .Iaddend. .Iadd.
 18. In a tractor which has steering clutches and steering brakes, the combination comprising: actuating pedals for said clutches and brakes; linkage to release one clutch upon depression of one pedal and to apply the corresponding brake upon further depression of said one pedal; similar linkage between the other clutch and brake and the other pedal; each said linkage including a first linkage to release the corresponding clutch, and a second separate linkage from each of said actuating pedals to the corresponding brake; a third pedal located between the other actuating pedals; means operable upon depression thereof to apply both brakes only; and the means operable upon depression of the third pedal including the second separate linkages but not the first linkages, and a member operatively connected to the third pedal for engaging both said second separate linkages to equalize brake applying pressure. .Iaddend. 